Amblyopia, commonly known as lazy eye, is the eye condition noted by reduced vision not correctable by glasses or contact lenses and is not due to any eye disease. The brain, for some reason, does not fully acknowledge the images seen by the amblyopic eye. This almost always affects only one eye but may manifest with reduction of vision in both eyes. It is estimated that three percent of children under six have some form of amblyopia.
Both eyes must receive clear images during the so-called critical period, i.e. between birth to 6 years of age. Anything that interferes with clear vision in either eye during this critical period can result in amblyopia, i.e. a reduction in vision not corrected by glasses or elimination of an eye turn. The most common causes of amblyopia are constant strabismus (constant turn of one eye), anisometropia (different prescriptions in each eye), and/or blockage of an eye due to trauma, lid droop, etc. If one eye sees clearly and the other sees a blur, the good eye will inhibit (block, suppress, ignore) the eye with a blur. Thus, amblyopia is a neurologically active process. This inhibition results in a permanent decrease in the vision in that eye that is not corrected just with glasses.
Because amblyopia usually occurs in one eye only, many children may be unaware of the condition. As far too many parents fail to take their infants and toddlers in for an early comprehensive vision examination, many children go undiagnosed until they have their eyes examined at the eye doctor's office at a later age. The most important diagnostic tools are the special visual acuity tests other than the standard letter charts used by the eye doctor. Examination with cycloplegic drops can be necessary to detect this condition in the young.
If not detected and treated early in life, amblyopia can cause a permanent loss of vision with associated loss of stereopsis (two eyed depth perception). Detection and correction before the age of two offers the best chance for restoration of normal vision. Amblyopia can be treated fairly successfully between the ages of 2 and 6, but the success decreases with age. The best results from treatment occurs between ages 6 months. to 2 years.
Eye patches have long been a standard treatment for amblyopia. Typically, an ophthalmologist prescribes covering the “strong” eye with the eye patch for several hours during the day when the patient is constantly using his/her eyes. By covering the “strong” eye, the “lazy” eye is forced into service. Forced use of the “lazy” eye tends to strengthen that eye, and thus ameliorate the symptoms of amblyopia.
Children and parents alike, however, sometimes have difficulty following through. Even if the child is initially enthusiastic about looking like a pirate, consistently wearing an eye patch for a prescribed time period each day for days, weeks, or months, can become burdensome leading to non-compliance.
When a patient returns to the ophthalmologist for follow-up care, the physician would like to know, with some degree of accuracy, how long the patient actually wore the eye patch in the intervening time period since the previous examination. For example, if the patient reports wearing the eye patch for 5 hours daily for thirty days, and the physician does not observe the hoped-for improvement in the “lazy eye,” then the physician might ask the patient to wear the eye patch for more hours each day. On the other hand, if the patient reports that he/she did not diligently follow the 5 hour per day treatment regime, then the physician might not increase the daily patch interval. Rather, the physician might counsel the patient about the necessity to follow through with the prescribed treatment protocol. Patient averments, and/or the averments made by the parents of the patient, regarding how long the patient actually wore the patch each day are typically inaccurate.